Esc menu without "Exportieren"; export screen mod removed

- cUI_EscMenu::BuildLines hook: the UI_ESC_EXPORT line is removed, the
  lines below move up, the window shrinks by one line, centred.
- game/ui/control.h: control vector helpers (ControlsIn, RemoveControl,
  SetControlAt, DeleteControl, ControlNamed), used by the main menu too.
- The export screen is unreachable now: charexport.cpp and
  docs/char-export.md deleted. Spielen screen redesign noted in todo.md.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/characters.md

@@ -258,6 +258,14 @@ flag +0x54 |= 0x40. The Esc menu line keeps its action (Show
 direct save while a game runs. Its text is patched at 0x6bc1f7 (id 0x41b is
 used by other windows too). Loading is from the main menu only.
 
+The Esc menu has no "Exportieren" (request 2026-10-20): `cUI_EscMenu::BuildLines`
+(0x6bb870, called by the constructor and on an event) makes five
+cUI_StaticText64 lines in the vector +0x158, 0x24 apart; each handles its own
+events. After it the UI_ESC_EXPORT line is removed and deleted, the lines
+below move up, and the window (0x108 x 0xc8) loses 0x24 of height, staying
+centred. With it the export screen (cUI_Character mode 5) is unreachable;
+its mod (charexport.cpp, an erase button for export slots) was deleted.
+
 ### Migration
 
 On first start (no `characters\` folder): after a backup in
@@ -268,7 +276,6 @@ kept, the newest file overall is the shared hero.
 ## Open
 
 - Reset a difficulty.
-- Remove the export / import UI.
 - Silent autosave every 10 minutes.
 - Quickload (row 0) does not know characters.
 - Multiplayer (see `todo.md`).